Well, looks like 0.3.0.2 was not the last 0.3.0 release after all. coekie found an issue with CTCP handling in Quassel Core that allows attackers to send arbitrary IRC messages on your behalf. This issue is present in all versions prior to 0.3.0.3 and Git older than October 26th (rev. d7a0381).

A CTCP ping where the value contains a CTCP quoted newline (’20′ + ‘n’) will let the Quassel core reply with a message containing an unquoted newline (‘\n’). The IRC server interprets this as a command separator.

Having a newline seperator injected in your IRC session means that anybody that sends a carefully crafted, malicious CTCP ping to your vulnerable client will be able to add an arbitrary command to it that will be executed with your privileges by the client – just as if you had typed it yourself.

The vulnerability is patched in version 0.3.0.3 which is available for download here.

As noted on the homepage, some distributions already have the new version available in their package repositories, other should update manually.

Gentoo and *buntu already ship the new version, with more distributions hopefully following ASAP. If you still use a 0.2-rc1 core, please consider updating to 0.3.x as soon as possible. Note that we provide unstable, but fixed packages for Debian now, thanks to dileX.